The Ambient Air Quality Directives require the assessment of the ambient air quality in Member States based on common methods and criteria for air quality monitoring and modelling. This comprehensive assessment is required throughout the whole territory of each country. The assessments should be done in a way so that they are representative of other locations. Find out more about spatial representativeness.
When air quality monitoring is being used for air quality assessment, it is extremely important to appropriately site sampling points. This ensures monitoring information can be used to obtain further information on:
- Exposure of the population to air pollutants
- Source apportionment that supports the development of air policy
- Air pollution management in the area
Key provisions
Amongst other key provisions, Directive (EU) 2024/2881:
- Requires that air quality zones be classified according to an assessment regime that defines which assessment methods are required.
- Establishes a minimum number of sampling points for regulated pollutants, ultrafine particles (UFPs), and for the additional pollutants of Annex VII.
- Establishes the criteria for the locations of these sampling points.
- Allows Member States to subtract the contribution of natural sources under certain conditions before comparing the ambient air pollutant concentrations to the limit values. See the Guidelines and the 2022 assessment study for more information.
- Allows Member States to subtract particulate matter - PM10 attributable to winter-sanding or winter-salting of roads when assessing compliance with air quality limit values, provided that reasonable measures have been taken to lower concentrations. See the Guidelines for more information.
Guidance and technical support documents
To implement the Ambient Air Quality Directives, several guidance and technical support documents have been prepared, with extensive input from national experts.
- Technical support document on the use of reference and non-reference methods, and on the quality assurance process to meet relevant data quality objectives for regulated air pollutants
- Technical support document on the use of modelling for various application domains under the Ambient Air Quality Directive
- Support document on setting up common measuring stations for PM2.5 under Directive 2008/50/EC on ambient air quality and cleaner air for Europe
- Guidance report on Preliminary Assessment under EC Air Quality Directives
- Guidance on Assessment under the EU Air Quality Directives
- Decision 2004/279/EC, guidance for implementing the ozone directive
- Guidance on assessment around point sources
Additionally, to support implementation, these studies and assessments have been conducted.
- An analysis of the minimum number of sampling points (Member State-specific reports are available on the right-hand side menu): The assessment analyses the state of the air quality monitoring network in place in each Member State, against the requirements of the revised Ambient Air Quality Directive (EU)2024/2881. The aim is to identify gaps that the Member States would need to address to comply with selected monitoring requirements under the revised Directive. The data used is for the period 2019- 2023.
- A study assessing the siting of air quality sampling points at industrial sites evaluates the placement of air quality monitoring sampling points near industrial sources to ensure a harmonised application of criteria across the European Union and verify that the highest exposure of the general population to air pollution from industrial sources is measured in all air quality zones. The interactive map viewer provides a convenient way to examine individual industrial sources and monitoring stations, which can be valuable for independent assessment by national experts.
Reference air quality measurement methods
For regulated pollutants, a reference measurement method has been prescribed, which can be found in Annex VI of the Ambient Air Quality Directive (EU) 2024/2881. The situation has evolved and the following reference measurement methods have been updated since the adoption:
- Benzene part 1 EN 14662: 2023
- Ozone: EN14625:2024
The standards can be obtained through the national standardisation organisation here.
Non-reference measurement methods can also be used provided they respect provisions for equivalence set out in the Directives (Annex VI). A Commission Working Group on Equivalence has prepared a document describing principles and methodologies to be used to demonstrate the equivalence of alternative (non-reference) measurement methods to the reference methods described by the EN Standard methods:
The corresponding tool to facilitate the use of the guidance (in particular for checking the equivalence of non-reference methods for PM-monitoring) has been developed. The updated version is now available:
The technical support document on the use of reference and non-reference methods provides information on measurement related matters for all regulated pollutants in the AAQD. This includes description of measurement methods, data quality objectives, Quality Assurance and Quality Control (QA/QC) for fixed and indicative measurements and considers objective estimation. The document also gives advice on best practices and references other sources of information where applicable.
Air quality modelling
Air quality modelling applications are considered to provide supplemental information to air quality monitoring by enabling point data (e.g. from fixed measurements) to be interpreted in terms of the geographical distribution of concentrations.
In addition to air quality assessments, modelling applications can provide more comprehensive information on public exposure, support the identification of sources, inform air quality plans and roadmaps, and perform future projections based on different measures scenarios.
The Technical support document on the use of modelling for various application domains provides support for the use of modelling systems under various application domains mentioned by the AAQD.
A Forum for AIR quality Modelling (FAIRMODE) of modellers and users has been established. It aims in bringing together air quality modelers and users in order to promote and support the harmonized use of models by EU Member States, with emphasis on model application under the European Air Quality Directives. The FAIRMODE webpage contains links to its current activities.
Objective estimation of air quality
The Ambient Air Quality Directives also allow for objective estimation as an air quality assessment method for air quality zones with very good air quality. By identifying local pollution sources and information on regional air quality, an estimation of the concentration of a regulated pollutant is made.
Ensuring the quality of assessment information either generated through monitoring, modelling, or objective estimation is one of the paramount provisions of the Directive. Data quality objectives are prescribed with the aim of defining maximum allowed uncertainty and data coverage (proportion of the calendar year for which there is valid data).
Member States are responsible for ensuring appropriate quality assurance of the assessment as well as the appropriate quality control of the information provided to the public and through the assessment reports. The Commission has set-up a community-wide process, managed by the Joint Research Centre (JRC).
AQUILA is a network of national reference laboratories that provides expert advice to the Commission. In its website you may find more information on its objectives, support documents, and quality assurance procedures and programmes. It has prepared an extensive document that summarises the roles and responsibilities of the national reference laboratories and of the network itself, describes the quality assurance procedures and makes EU-wide comparisons.
The European Environment Agency (EEA) together with EIONET and its Topic Centre also supports quality assurance of the data and reporting of air quality assessment information.